Download Fluorescence In Situ Hybridization

Research Techniques Made Simple:
Fluorescence In Situ Hybridization
(FISH)
Amy Y-Y Chen, MD
Andrew Chen, MD
1
2
Department of Dermatology, Boston University School of Medicine, Boston, MA, USA
Division of Plastic and Reconstructive Surgery, Department of Surgery, Henry Ford Health System
and Wayne State University, Detroit, MA, USA
What is FISH?
• A technique used to detect the presence
or absence and location of specific gene
sequences
• Can visualize specific cytogenetic
abnormalities (copy number aberrations)
– chromosomal deletion, amplification,
translocation
Principles of FISH
Schematic diagram for FISH technique
(Reprinted with permission from O'Connor, 2008. Fluorescence in situ hybridization (FISH). Nature Education 1(1).
Interpretation of FISH
• Each fluorescently labeled probe that hybridizes
to a cell nucleus in the tissue of interest will
appear as a distinct fluorescent dot
– Diploid nuclei will have two dots
– If there is duplication in the region of interest, the gain
will result in more than two dots
– If there is a loss in the region of interest, one or zero
dot will result
FISH in Dermatology
• Most significant in
melanoma
• Image: As presented by
Bastian et al (J Invest
Dermatol 113:1065-1069,
1999)
FISH in Dermatology
• Pham-Ledard et al (J Invest Dermatol 130:816-825, 2010)
IRF4 locus-specific fluorescence in situ hybridization (FISH) strategy. (a) Schematic representation of all BAC clones
hybridizing to the 6p25 region used in this study. RP11-119L15, CTD-2317K17, and CTD-3052J12 BAC clones, which
showed nonspecific hybridization on chromosome 16, were discarded. The break-apart BAC probe strategy used
CTD-2308G5 as the 5′ IRF4 BAC probe and RP11-164H16 as the 3′ IRF4 BAC probe. (b) The FISH signal pattern
expected in interphase nuclei samples. Normal nuclei would exhibit a two-fusion (2F) signal pattern corresponding
to the juxtaposition of BAC clones probes. Nuclei with an IRF4 locus break point, suggesting translocation, would
show a split signal pattern (1F-1R-1G). Nuclei with extra copies of a non-rearranged IRF4 locus should exhibit more
than a 2F signal pattern.
FISH in Dermatology
• Pham-Ledard et al (J Invest
Dermatol 130:816-825, 2010)
Histological, immunophenotypical, and fluorescence in situ
hybridization (FISH) aspects of three typical cases with and
without IRF4 locus rearrangement. Left panel: Lymph node
section of cutaneous anaplastic large cell lymphoma (C-ALCL)
without IRF4 locus rearrangement. (a) Hematoxylin eosin and
safran (HES). Scale bar=20 m. (b) Positivity of CD30
immunostaining. (c) Immunostaining shows expression of
multiple myeloma antigen 1 (MUM1) by more than 85% of tumor
cells. (d) Normal FISH signal pattern (2F). Scale bar=5 m.
Middle panel: Skin section of case 6 with C-ALCL and IRF4
rearrangement. (e) HES, x400. (f) Positivity of CD30
immunostaining. (g) Immunostaining shows MUM1 expression
by more than 85% of tumor cells. (h) Split FISH signal pattern
(1F-1R-1G). Scale bar=5 m. Right panel: Skin section of case 8
with transformed mycosis fungoide and IRF4 locus
rearrangement. (i) HES, x400. (j) Positivity of CD30
immunostaining. (k) Immunostaining shows MUM1 expression
by 10–50% of large tumor cells. (l) FISH signal pattern shows an
extra signal of SpectrumGreen-labeled RP11-164H16 (2F+1 G
extra signal), indicating that the break point maps to the 6p25
region in the genomic area corresponding to the RP11-164H16
sequence. Scale bar=5 m.
FISH: Advantages
• Can be used in formalin-fixed, paraffin embedded
sections or fresh frozen tissue
• Possible correlation between FISH result and
tumor morphology with conventional light
microscopy
• Allows simultaneous interrogation of multiple
cytogenetic signatures
• Can be used either in bulky tumors or tumors
where the malignant component contributes to a
small proportion of the overall cellular population
FISH: Limitations
• Probe design requires knowledge of specific
chromosomal abnormalities to be studied
• Cutoff signals may be different among
laboratories
• Processing errors, imperfect hybridization, nonspecific binding, photobleaching, interobserver
variability, and false positive and negative results
are possible
FISH: Summary
• FISH is a technique used to visualize specific
cytogenetic abnormalities
• It can serve as a supplementary diagnostic tool in
pigmented lesions. However, should not be used
as a stand-alone test
• Cannot replace traditional histopathologic
analysis
• FISH result must correlated with clinical,
pathologic and molecular information